Magnetic and cryogenic magnetocaloric properties of GdPO4 nanorods

• Published in: Journal of magnetism and magnetic materials 2021-02, Vol.519, p.167452, Article 167452
• Main Authors: Yu, Y.Y., Petrov, Dimitar N., Park, K.C., Huy, B.T., Long, Phan The
• Format: Article
• Language: English
• Subjects: Antiferromagnetism; Cooling; Crystal structure; Entropy; Ferromagnetism; Gadolinium compounds; GdPO4 nanorods; Hydrothermal crystal growth; Image transmission; Lanthanide phosphates; Low temperature; Magnetic properties; Magnetization; Magnetocaloric effect; Nanorods; Single crystals
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2020.167452

•Magnetic and magnetocaloric (MC) properties of GdPO4 nanorods.•Large values of MC parameters with ΔSmmax = 56.2 J/kg.K and RCP = 415.9 J/kg.•GdPO4 nanorods show a second-order phase transition and short-range magnetic ordering.•A comprehensive comparison with MC parameters of typical cryogenic MC materials. A sample of GdPO4 nanorods (NRs) with average diameter about 20 nm and length 150 nm has been prepared by a hydrothermal method. The analyses of the XRD pattern and transmission electron microscopy images have proved that the NRs are single crystals with a hexagonal structure. The variations of the magnetization versus temperature and magnetic field have confirmed magnetic ordering at low temperatures. The assessment of the magnetocaloric effect from the magnetization isotherms, M(H), in the temperature range T = 2 – 25 K has revealed a strong increase of the magnetic entropy change (|ΔSm|) below T = 15 K with increasing H. The magnetic entropy change reaches maximum (|ΔSmmax|) at temperatures T = 2 – 2.7 K, around a ferromagnetic–paramagnetic transition. It has been found that the relative cooling power (RCP) and refrigerant cooling (RC) increase with increasing H by the broadened linewidth of the |ΔSm(T)| curve. At H = 60 kOe, the values of ΔSmmax and RCP (or RC) are about 56.2 J/kg⋅K and 415.9 (296.5) J/kg, respectively. Our analyses also have inferred that the GdPO4 NRs exhibit a short-range magnetic order with coexisting ferromagnetic and antiferromagnetic interactions.